18if __name__ ==
"__main__":
21 from gams.magic
import GamsInteractive
22 gams = GamsInteractive()
26 m = gams.exchange_container
29 sites = m.addSet(
'sites', records = [
"1",
"2",
"3"])
30 mills = m.addSet(
'mills', records = [
"Mill A",
"Mill B",
"Mill C"])
31 dist = m.addParameter(
'dist', [sites, mills], records = np.array([[ 8,15,50],
34 supply = m.addParameter(
'supply', [sites], records = np.array([20,30,45]))
35 demand = m.addParameter(
'demand', [mills], records = np.array([30,35,30]))
36 cost_per_haul = m.addParameter(
'cost_per_haul', records = 4)
40 m.addAlias(
'm', mills)
41 ship = m.addVariable(
'ship',
'positive', [sites, mills])
42 obj = m.addVariable(
'obj',
'free')
47Equation defcost; defcost.. cost_per_haul*sum((s,m), ship(s,m)*dist(s,m)) =e= obj;
48Equation defsupply; defsupply(s).. sum(m, ship(s,m)) =e= supply(s);
49Equation defdemand; defdemand(m).. sum(s, ship(s,m)) =e= demand(m);
51model millco / all /;''')
54 gams.gams(
'solve millco min obj using lp;')
57 print(m[
"ship"].pivot())
58 print(f
'Total cost will be {obj.records["level"][0]}')
61 gams.create(
'genmodel')
62 m = gams.exchange_container
65 i = m.addSet(
'i', records = [
'i'+str(i)
for i
in range(6)], description =
'equation index')
66 j = m.addSet(
'j', records = [
'j'+str(j)
for j
in range(9)], description =
'variable index')
67 A = m.addParameter(
'A', [i,j], records = np.array([[1,1,1,0,0,0,0,0,0],
72 [0,0,1,0,0,1,0,0,1]]))
73 b = m.addParameter(
'b', [i], records = np.array([20,30,45,30,35,30]))
74 c = m.addParameter(
'c', [j], records = np.array([8,15,50,10,17,20,30,26,15]))
75 x = m.addVariable(
'x',
'positive', [j])
76 obj = m.addVariable(
'obj',
'free')
81Equation defobj; defobj.. 4*sum(j, c(j)*x(j)) =e= obj;
82Equation e(i); e(i).. sum(j, A(i,j)*x(j)) =e= b(i);
87 gams.gams(
'solve gen min obj using lp;')
91 print(f
'Total cost will be {obj.records["level"][0]}')
94 gams.gams_cleanup(closedown=
True)
